The purpose of this study is to develop and test an emergency room x-ray screening protocol for extremity injuries aimed at reducing the number of unnecessary x-rays without adversely affecting the quality of care. Data from a series of patients treated in an emergency room for an upper or lower extremity injury will be analyzed in order to identify the clinical variables best able to discriminate between patients with and without fractures. The resulting statistical model will form the basis of an x-ray screening protocol which, after careful review for safety and clinical acceptability by a panel of orthopedic surgeons and radiologists, will be tested on a new series of patients to assess its impact on the cost and quality of care. The protocol will be used to place each patient into a "high-risk" or "low-risk" category, and only high-risk patients will be selected for radiographic examination. The low-risk group will be managed coservatively so that, in the unlikely event that a patient in this group has a fracture, the patient's treatment, instructions, and follow-up will lead to satisfactory healing and avoid adverse consequences. At the end of the model implementation phase, the results will be evaluated to determine the impact of the model on the yield of positive x-rays, the cost of treatment, the efficiency of the emergency service, and the quality of care. It the model proves successful at reducing unnecessary x-rays while maintaining high-quality care, then the model criteria will serve as a foundation for an extremity injury management algorithm to be used for medical education and quality appraisal within the Yale Trauma Program's Quality Assurance System.